Build a Cinema Ticketing System

Tables: movies, showtimes (movie_id, hall, date, time, seat_map), seats (showtime_id, row, number, category, price, status, reserved_by, reserved_until), bookings (customer_email, showtime_id, seat_ids[], total, status, paystack_ref), tickets (booking_id, seat_id, qr_code).

async function reserveSeats(customerId, showtimeId, seatIds) {
  // Check all seats are available
  var seats = await db.seats.findMany(seatIds);
  var unavailable = seats.filter(s => s.status !== 'available');
  if (unavailable.length > 0) throw new Error('Some seats are no longer available');

  var reservedUntil = new Date(Date.now() + 10 * 60 * 1000); // 10 min

  // Atomic update using transaction
  await db.transaction(async (trx) => {
    for (var seatId of seatIds) {
      await trx.seats.update(seatId, {
        status: 'reserved',
        reserved_by: customerId,
        reserved_until: reservedUntil,
      });
    }
  });

  var total = seats.reduce((sum, s) => sum + s.price, 0);
  return { total, reservedUntil };
}

// Cron job: release expired reservations every minute
async function releaseExpiredReservations() {
  await db.seats.updateWhere(
    { status: 'reserved', reserved_until_lt: new Date() },
    { status: 'available', reserved_by: null, reserved_until: null }
  );
}

var QRCode = require('qrcode');

async function initiatePayment(customerId, customerEmail, showtimeId, seatIds) {
  var seats = await db.seats.findMany(seatIds);
  var total = seats.reduce((sum, s) => sum + s.price, 0);
  var reference = 'TKT-' + Date.now();

  var booking = await db.bookings.create({
    customer_email: customerEmail, showtime_id: showtimeId,
    seat_ids: seatIds, total, status: 'pending', paystack_ref: reference,
  });

  var res = await fetch('https://api.paystack.co/transaction/initialize', {
    method: 'POST',
    headers: { Authorization: 'Bearer ' + process.env.PAYSTACK_SECRET_KEY, 'Content-Type': 'application/json' },
    body: JSON.stringify({
      email: customerEmail, amount: total, currency: 'NGN',
      reference, metadata: { booking_id: booking.id },
    }),
  });
  return (await res.json()).data.authorization_url;
}

// Webhook: confirm booking and generate tickets
if (event.event === 'charge.success') {
  var bookingId = event.data.metadata.booking_id;
  var booking = await db.bookings.findById(bookingId);

  await db.bookings.update(bookingId, { status: 'confirmed' });
  await db.seats.updateMany(booking.seat_ids, { status: 'sold' });

  // Generate one QR code per seat
  for (var seatId of booking.seat_ids) {
    var ticketRef = bookingId + '-' + seatId;
    var qrCode = await QRCode.toDataURL(ticketRef); // base64 PNG
    await db.tickets.create({ booking_id: bookingId, seat_id: seatId, qr_code: qrCode, ref: ticketRef });
  }

  await sendTicketEmail(booking.customer_email, bookingId);
}

See build a ticketed webinar platform for the same payment-before-access pattern applied to online events.

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